JP5811441B2 - Image forming apparatus and transfer unit - Google Patents

Description

  According to the present invention, an image for correcting the image forming condition of the toner image forming unit based on the result of detecting the optical characteristic of the region where the predetermined test toner image is formed in the entire area of the surface endless moving body by the optical sensor. The present invention relates to a forming apparatus. The present invention also relates to a transfer unit used in such an image forming apparatus.

  Conventionally, image formation that corrects image formation conditions such as development bias and latent image writing timing based on the result of detecting the optical characteristics of a test toner image formation region on an endless moving body such as an intermediate transfer belt by an optical sensor The device is known.

  For example, the image forming apparatus described in Patent Document 1 transfers a test toner image formed on the surface of a photoreceptor by an optical writing process or a developing process onto the surface of a transfer belt that moves endlessly. Then, based on the result of detecting the toner adhesion amount per unit area in the test toner image on the transfer belt by the reflection type photosensor as an optical sensor, the optical writing intensity and the developing bias for the photoconductor are corrected. As a result, the target image density can be stably obtained regardless of environmental changes over time.

  The image forming apparatus described in Patent Document 2 is based on the detection result of the reflection type photosensor, and the relative positions of the Y (yellow), M (magenta), C (cyan), and K (black) toner images. Know the gap. More specifically, the image forming apparatus arranges and transfers the misregistration detection toner images formed on the four photoreceptors for Y, M, C, and K side by side on the intermediate transfer belt, and detects the misalignment detection pattern. Get. Then, based on the timing at which each color misregistration detection toner image in the misregistration detection pattern is detected by the reflective photosensor, the relative misregistration of each color toner image is grasped. Next, based on the grasped result, the latent image writing start timing for each color photoconductor is corrected to reduce the positional deviation of each color toner image. As a result, the positional deviation of each color toner image can be kept within a predetermined range regardless of environmental fluctuations over time.

  In such an image forming apparatus using an optical sensor, when a foreign matter such as toner or dust adheres to the detection portion (light entrance / exit window) of the optical sensor, the toner image and the toner adhesion amount can be detected with high accuracy. It becomes impossible. Therefore, the image forming apparatus described in Patent Document 3 is provided with an openable / closable shutter member that covers the detection unit of the optical sensor. When the test toner image is not detected, the detection unit is covered with the shutter member, so It is designed to suppress the adhesion of.

  Further, in this image forming apparatus, the number of parts is reduced by sharing the drive motor with the contact / separation mechanism of the secondary transfer roller with respect to the intermediate transfer belt and the shutter member. Specifically, the secondary transfer roller is in contact with the intermediate transfer belt while being held by a swingable holding body, thereby secondary transfer nip for secondary transfer of the toner image from the belt to the recording paper. Is formed. An eccentric cam is in contact with the swingable holding body holding the secondary transfer roller. Further, a shutter member that can swing from the side opposite to the holding body is pressed against the eccentric cam. When the eccentric cam rotated by the drive motor stops rotating at a position where the large diameter portion abuts the holding body, the secondary transfer roller held by the holding body is separated from the intermediate transfer belt. At this time, the eccentric cam makes the small diameter portion contact the shutter member. In this state, the shutter member is retracted from the position facing the detection unit of the reflective optical sensor to expose the detection unit. On the other hand, when the eccentric cam stops rotating at a position where the small-diameter portion abuts the holding member, the holding member moves in a direction approaching the intermediate transfer belt to bring the secondary transfer roller into contact with the intermediate transfer belt. At the same time, the eccentric cam abuts the large diameter portion on the shutter member, and moves the shutter member to a position facing the detection unit of the reflective photosensor. Thereby, the detection unit is closed by the shutter member. In this configuration, when the test toner image is formed on the intermediate transfer belt, the secondary transfer roller is separated from the intermediate transfer belt to avoid the transfer of the test toner image to the secondary transfer roller, and the reflection type photosensor. Thus, the toner image can be detected by exposing the detection unit.

  However, in this image forming apparatus, since both the shutter member and the secondary transfer roller holder need to be in contact with the eccentric cam, the shutter member and the holder are arranged at a short distance from each other. To adopt a layout to do. As a result, there is a problem that the degree of freedom in layout is lowered.

  When the drive source is shared by the shutter member and the contact / separation mechanism of any contact / separation member that contacts / separates not only the contact / separation operation of the secondary transfer roller but the surface endless moving body such as an intermediate transfer belt, Similar problems can arise. For example, in an image forming apparatus that superimposes and transfers a toner image of a photoconductor of each color onto a recording paper held on the surface of an endless paper conveyance belt, in order to increase the recording paper holding force on the belt surface, There is known one in which a bias roller is brought into contact with a belt surface. In such a configuration, when the drive source is shared by the contact / separation mechanism of the bias roller and the shutter member, the same problem occurs.

  The present invention has been made in view of the above background, and an object thereof is to provide the following image forming apparatus and transfer unit. In other words, the image forming apparatus can reduce the number of parts by sharing the driving source and can improve the degree of freedom of layout as compared with the related art.

In order to achieve the above-mentioned object, the invention of claim 1 hangs around a toner image forming means for forming a toner image on the surface of the image carrier and a plurality of stretching members disposed inside the loop. The surface of the endless belt member that can be moved endlessly in an endless state is moved endlessly along a path for entering the position facing the image carrier, and the toner image on the image carrier at the facing position is moved to the belt member. Transfer means for transferring to the surface of the recording medium or a recording material held on the surface, and an optical characteristic of a region where a predetermined test toner image is formed in the entire region in a direction orthogonal to the moving direction of the belt member . Based on an optical unit to detect, an optical unit having a holding member for holding the optical sensor, a shutter member for opening and closing a detection unit of the optical sensor, and a detection result by the optical sensor And condition correcting means for correcting the image forming conditions of the toner image forming means, and toward and away from contacting and spacing member to the surface of the belt member, the shutter member or its linked shutter connecting member, and the contacting and spacing member or of separable coupling member coupled thereto, the shutter member or the the shutter connecting member only push per disposed so that, by varying the amount of pushing by a change in its posture, the shutter Of the shutter pressing member for operating the material, the shutter member or the shutter connecting member, and the contacting / separating member or the contacting / separating connecting member, the shutter pressing member is arranged so as to be pressed against only the contacting / separating member or the contacting / separating connecting member. is set, by changing the amount of pushing by the change in its attitude, the member pressing separable operating said moving assembly, the shutter Exert a driving force for driving the pressing member and the contact and separation pressing member, an image forming apparatus and a drive source shared in the shutter pressing member and the contact and separation pressing member, said loop inside The shaft is disposed so as to extend along the width direction of the belt member, and among the plurality of stretching members, the rotation is performed in a posture in which the axial direction of the belt member is along the width direction. A first idling gear that idles on the circumferential surface of the first shaft portion that is a shaft portion on one end side in the axial direction of the drive roller that moves the belt member endlessly, and an axis on the other end side in the axial direction of the drive roller A second idling gear that idles on the peripheral surface of the second shaft portion that is a portion, a first shaft gear that is fixed to an end on one end side in the axial direction of the shaft so as to mesh with the first idling gear, The second A second shaft gear fixed to the other end side in the axial direction of the shaft so as to mesh with the idling gear, and the cam surface of the contacting / separating member or the contacting / separating connecting member in the width direction is provided. The first eccentric cam as the contact / separation pressing member that is pressed against the one end side portion is idled on the peripheral surface of the first shaft portion together with the first idle gear, and the cam surface is contacted / separated. The second eccentric cam as the contact / separation pressing member that is brought into contact with the other end portion in the width direction of the member or the contact / separation connecting member idles on the peripheral surface of the second shaft portion together with the second idle gear. It is characterized by the fact that it has been allowed to.
Further, the invention of claim 2, the image forming apparatus according to claim 1, as the shutter pressing member, comprising a taper extending along the its rotational direction at one end of its rotational axis direction, the shutter member Alternatively, the one that changes the amount of pressing by changing its own rotation stop position while pressing the taper against one end or the other end in the width direction of the shutter connecting member is used. is there.
According to a third aspect of the present invention, in the image forming apparatus of the second aspect , the optical unit is a plurality of optical units arranged at different positions in the width direction and at different positions in the moving direction of the belt member. And a guide that guides the shutter member pushed in the width direction by the taper along an inclined direction that is a direction inclined from the width direction while being along the surface of the belt member. The number of optical sensors in the state where the detection unit is closed by the shutter member is changed by changing the position of the shutter member in the tilt direction by changing the pressing amount. It is characterized by.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the shutter member is moved in parallel along the surface of the detection unit, and is fixed to the shutter member. Along with the movement with the shutter member, there is provided a cleaning member for performing a cleaning process by rubbing on the surface of the detection portion.
According to a fifth aspect of the present invention, the surface of an endless belt member that is endlessly moved in a state where it is wound around a plurality of stretching members disposed inside the loop of the own is opposed to the image carrier. A transfer means for transferring the toner image on the image carrier onto the surface of the belt member or a recording material held on the surface at the opposite position while moving endlessly along a path to enter the belt ; An optical sensor that detects an optical characteristic of a region where a predetermined test toner image is formed out of the entire region in a direction orthogonal to the moving direction, a holding body that holds the optical sensor, and a shutter member that opens and closes the detection unit of the optical sensor an optical unit including an, said belt and toward and away from contacting and spacing member to the surface of the member, the shutter member or its linked shutter connecting member, and said moving assembly Of separable coupling member coupled thereto, the shutter member or the the shutter connecting member only push per disposed so that, by varying the amount of pushing by a change in its posture, the shutter a shutter pressing member to operate the section member, the shutter member or the shutter connecting member, and one of the contacting and spacing member or the connecting and disconnecting the connection member, as pressed against only the contacting and spacing member or the connecting and disconnecting coupling member A contact / separation pressing member that operates the contact / separation member, and the shutter pressing member and the contact / separation pressing member for driving the contact / separation member by changing a pressing amount according to a change in the posture of the device; exert a driving force, in the transfer unit and a driving source shared with the shutter pressing member and the contact and separation pressing member, the Le The shaft is arranged so as to extend along the width direction of the belt member on the inner side of the belt, and of the plurality of stretching members, the shaft is rotated in a posture in which the axial direction is along the width direction. A first idling gear that idles on the peripheral surface of the first shaft portion that is a shaft portion on one end side in the axial direction of the drive roller that moves the belt member endlessly, and the other end side in the axial direction of the drive roller A second idling gear that idles on the peripheral surface of the second shaft portion that is the shaft portion of the first shaft gear, and a first shaft gear that is fixed to an end portion on one end side in the axial direction of the shaft so as to mesh with the first idling gear And a second shaft gear fixed to an end portion on the other end side in the axial direction of the shaft so as to mesh with the second idling gear, and the cam surface thereof is the contact / separation member or the contact / separation connection member One end side in the width direction of The first eccentric cam as the contact / separation pressing member that presses against a location is idled on the peripheral surface of the first shaft portion together with the first idle gear, and the cam surface of the first eccentric cam is the contact / separation member or The second eccentric cam as the contact / separation pressing member to be brought into contact with the other end portion of the contact / separation connecting member in the width direction is idled on the peripheral surface of the second shaft portion together with the second idler gear. it is characterized in that the the.

In these inventions, the pressing member for moving the shutter member and the contact / separation member according to the change of its own posture, the shutter pressing member for moving the shutter member, and the contact / separation pressing for moving the contact / separation member The contact member is provided separately. As a result, the restriction that the shutter member and the contact / separation member have to be arranged at a short distance from each other is eliminated, so that the degree of freedom in layout can be improved as compared with the prior art.
Moreover, the number of parts can be reduced by sharing the drive source between the shutter pressing member and the contact / separation pressing member.

1 is a schematic configuration diagram illustrating a printer according to an embodiment. FIG. 3 is an enlarged configuration diagram illustrating a process unit for Y of the printer. FIG. 2 is an enlarged configuration diagram illustrating an opening / closing door and a casing of the printer with the opening / closing door open. FIG. 2 is a block diagram showing a part of an electric circuit in the printer. FIG. 3 is a perspective view showing a transfer unit in a state where a K gradation pattern is formed on an intermediate transfer belt. FIG. 3 is a perspective view showing a transfer unit in a state where Y, M, and C gradation patterns are formed on an intermediate transfer belt. FIG. 3 is a plan view showing an intermediate transfer belt in a state where a position deviation detection pattern is formed. The side view which shows the optical sensor unit of a state which opened the shutter member with an intermediate transfer belt. The side view which shows the optical sensor unit of the state which closed the shutter member with an intermediate transfer belt. The top view which shows the optical sensor unit of the state which opened the shutter member from the downward direction. FIG. 3 is an enlarged perspective view showing a taper gear of the transfer unit. The top view which shows the optical sensor unit of the state which opened the shutter member from the downward | lower direction with the taper gear. The top view which shows the optical sensor unit of the state which closed the shutter member from the downward | lower direction with the taper gear. FIG. 4 is a partial perspective view partially showing a transfer unit in a state in which a secondary transfer bias roller is separated from an intermediate transfer belt. FIG. 4 is a partial perspective view partially showing a transfer unit in a state where a secondary transfer bias roller is in contact with an intermediate transfer belt. FIG. 4 is a partial perspective view showing a part of the transfer unit from the rear side. The side view which shows a part of transfer unit from the rear side. FIG. 4 is a partial perspective view showing a part of the transfer unit from the front side. The top view which shows partially the front side edge part of a transcription | transfer unit. The side view which shows the front side gear group of a transfer unit from the rear side. The top view which shows the state which opened the shutter member completely from the downward direction in the optical sensor unit of the printer which concerns on an Example. The top view which shows the same optical sensor unit of the state which opened the shutter member only half from the downward direction. The top view which shows the same optical sensor unit of the state which closed the shutter member completely from the downward direction.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described.
First, the basic configuration of the printer will be described. FIG. 1 is a schematic configuration diagram showing the printer. In this figure, the printer includes four image forming units 6Y, 6M, 6C, and 6K for generating toner images of yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and K). ing. These use toners of different colors as image forming substances, but other than that, they have the same configuration and are replaced when the lifetime is reached. Taking an image forming unit 6Y for forming a Y toner image as an example, as shown in FIG. 2, the image forming unit 6Y is a drum-shaped photoconductor 1Y as an image carrier, a drum cleaning device 2Y, a charge eliminating device (not shown). And a charging device 4Y, a developing device 5Y, and the like. The image forming unit 6Y is detached from the printer main body in the unit state.

  The charging device 4Y uniformly charges the surface of the photoreceptor 1Y that is rotated in the clockwise direction in the drawing by a driving unit (not shown). The surface of the uniformly charged photoreceptor 1 </ b> Y is exposed and scanned by the laser beam L to carry an electrostatic latent image for Y. This Y electrostatic latent image is developed by a developing device 5Y using a Y developer containing Y toner and a magnetic carrier to become a Y toner image. Then, primary transfer is performed on an intermediate transfer belt 8 described later. The drum cleaning device 2Y removes transfer residual toner adhering to the surface of the photoreceptor 1Y after the primary transfer process. The static eliminator neutralizes residual charges on the photoreceptor 1Y after cleaning. By this charge removal, the surface of the photoreceptor 1Y is initialized and prepared for the next image formation. Similarly, in the other color image forming units (6M, C, K), (M, C, K) toner images are formed on the photoreceptors (1M, C, K), and are formed on the intermediate transfer belt 8. Primary transfer is performed by superimposing.

  The developing device 5Y has a developing roll 51Y disposed so as to be partially exposed from the opening of the casing. Further, it also includes two conveying screws 55Y, a doctor blade 52Y, a toner density sensor (hereinafter referred to as T sensor) 56Y, and the like that are arranged in parallel to each other.

  In the casing of the developing device 5Y, a Y developer (not shown) including a magnetic carrier and Y toner is accommodated. The Y developer is carried on the surface of the developing roll 51Y while being agitated and conveyed by the two conveying screws 55Y and frictionally charged. Then, after the layer thickness is regulated by the doctor blade 52Y, the layer is transported to the developing region facing the Y photoreceptor 1Y, where Y toner is attached to the electrostatic latent image on the photoreceptor 1Y. This adhesion forms a Y toner image on the photoreceptor 1Y. In the developing unit 5Y, the Y developer that has consumed Y toner by the development is returned into the casing as the developing roll 51Y rotates.

  A partition wall is provided between the two transport screws 55Y. By this partition wall, the first supply unit 53Y that accommodates the developing roll 51Y, the right conveyance screw 55Y in the drawing, and the like, and the second supply unit 54Y that accommodates the left conveyance screw 55Y in the drawing are separated in the casing. . The right conveying screw 55Y in the drawing is driven to rotate by a driving means (not shown), and supplies the Y developer in the first supply unit 53Y to the developing roll 51Y while being conveyed from the near side to the far side in the drawing. The Y developer conveyed to the vicinity of the end of the first supply unit 53Y by the right conveyance screw 55Y in the drawing enters the second supply unit 54Y through an opening (not shown) provided in the partition wall. In the second supply unit 54Y, the left conveyance screw 55Y in the drawing is driven to rotate by a driving means (not shown), and the Y developer sent from the first supply unit 53Y is the right conveyance screw 55Y in the drawing. Transport in the reverse direction. The Y developer transported to the vicinity of the end of the second supply unit 54Y by the transport screw 55Y on the left side in the drawing passes through the other opening (not shown) provided in the partition wall, and the first supply unit. Return to 53Y.

  The above-described T sensor 56Y including a magnetic permeability sensor is provided on the bottom wall of the second supply unit 54Y, and outputs a voltage having a value corresponding to the magnetic permeability of the Y developer passing therethrough. Since the magnetic permeability of the two-component developer containing toner and magnetic carrier shows a good correlation with the toner density, the T sensor 56Y outputs a voltage corresponding to the Y toner density. This output voltage value is sent to a control unit (not shown). This control unit includes a RAM that stores a Vtref for Y that is a target value of an output voltage from the T sensor 56Y. The RAM also stores data for M Vtref, C Vtref, and K Vtref, which are target values of output voltages from a T sensor (not shown) mounted in another developing device. The Y Vtref is used for driving control of a Y toner conveying device to be described later. Specifically, the control unit drives and controls a Y toner conveying device (not shown) so that the value of the output voltage from the T sensor 56Y is close to the Y Vtref, and the Y toner in the second supply unit 54Y. To replenish. By this replenishment, the Y toner concentration in the Y developer in the developing device 5Y is maintained within a predetermined range. The same toner replenishment control using the M, C, and K toner conveying devices is performed for the developing units of the other process units.

  In FIG. 1 described above, an optical writing device 7 is disposed below the image forming units 6Y, 6M, 6C, and 6K. The optical writing device 7 serving as a latent image forming unit optically scans the respective photoreceptors in the image forming units 6Y, 6M, 6C, and 6K with a laser beam L emitted based on image information. By this optical scanning, electrostatic latent images for Y, M, C, and K are formed on the photoreceptors 1Y, 1M, 1C, and 1K. The optical writing device 7 irradiates the photosensitive member through a plurality of optical lenses and mirrors while scanning a laser beam (L) emitted from a light source with a polygon mirror rotated by a motor.

  On the lower side of the optical writing device 7 in the figure, a sheet storage means having a sheet storage cassette 26, a feeding roller 27 incorporated therein, and the like are disposed. The sheet storage cassette 26 stores a plurality of recording sheets P which are sheet-like recording bodies, and a feeding roller 27 is brought into contact with the uppermost recording sheet P. When the feeding roller 27 is rotated counterclockwise in the drawing by a driving means (not shown), the uppermost recording sheet P is sent out toward the sheet supply path 70.

  Near the end of the sheet supply path 70, a registration roller pair 28 is disposed. The registration roller pair 28 rotates both rollers so as to sandwich the recording sheet P. As soon as the registration roller 28 sandwiches, the rotation of both rollers is temporarily stopped. Then, rotation of both rollers is resumed at an appropriate timing, and the recording sheet P is sent out toward a secondary transfer nip described later.

  Above the image forming units 6Y, 6M, 6C, and 6K, there is disposed a transfer unit 15 that moves the intermediate transfer belt 8 as a surface endless moving body endlessly while stretching. The transfer unit 15 includes a secondary transfer bias roller 19 and a cleaning device 10 in addition to the intermediate transfer belt 8. Also provided are four primary transfer bias rollers 9Y, 9M, 9C, 9K, a driving roller 12, a cleaning backup roller 13, a secondary transfer nip entrance roller 14, and the like. The intermediate transfer belt 8 is endlessly moved in the counterclockwise direction in the figure by the rotational driving of the driving roller 12 while being wound around these seven rollers.

  The primary transfer bias rollers 9Y, 9M, 9C, and 9K hold the intermediate transfer belt 8 that is endlessly moved in this manner between the photoreceptors 1Y, 1M, 1C, and 1K, thereby forming primary transfer nips. ing. A primary transfer transfer bias having a polarity opposite to that of the toner (for example, plus) is applied to these primary transfer bias rollers. All of the rollers except the primary transfer bias rollers 9Y, 9M, 9C, and 9K are electrically grounded.

  The intermediate transfer belt 8 sequentially passes through the primary transfer nips for Y, M, C, and K along with the endless movement thereof, and Y, M, and C on the photoreceptors 1Y, M, C, and K are sequentially transferred. , K toner images are superimposed and primarily transferred. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the intermediate transfer belt 8.

  The drive roller 12 sandwiches the intermediate transfer belt 8 with the secondary transfer bias roller 19 as a contact / separation member to form a secondary transfer nip. The four-color toner image formed on the intermediate transfer belt 8 is transferred to the recording sheet P at the secondary transfer nip. Then, combined with the white color of the recording sheet P, a full color toner image is obtained.

  Untransferred toner that has not been transferred to the recording sheet P adheres to the intermediate transfer belt 8 after passing through the secondary transfer nip. This is cleaned by the cleaning device 10. The recording sheet P on which the four-color toner images are secondarily transferred at the secondary transfer nip is sent to the fixing device 20 via the post-transfer conveyance path 71.

  The fixing device 20 forms a fixing nip by a fixing roller 20a having a heat source such as a halogen lamp inside, and a pressure roller 20b that rotates while contacting the roller with a predetermined pressure. The recording sheet P fed into the fixing device 20 is sandwiched between the fixing nips so that the unfixed toner image carrying surface is in close contact with the fixing roller 20a. Then, the toner in the toner image is softened by the influence of heating and pressurization, and the full color image is fixed.

  The recording sheet P on which the full-color image is fixed in the fixing device 20 exits the fixing device 20 and then reaches a branch point between the paper discharge path 72 and the pre-reversal conveyance path 73. A first switching claw 75 is swingably disposed at this branch point, and the path of the recording sheet P is switched by the swing. Specifically, the path of the recording sheet P is set to the direction toward the paper discharge path 72 by moving the tip of the claw in a direction to approach the pre-reverse feed path 73. Further, by moving the tip of the claw away from the pre-reversing conveyance path 73, the path of the recording sheet P is changed to the direction toward the pre-reversing conveyance path 73.

  When the path to the paper discharge path 72 is selected by the first switching claw 75, the recording sheet P is disposed outside the apparatus after passing through the paper discharge roller pair 100 from the paper discharge path 72. Are stacked on a stack 50a provided on the upper surface of the printer housing. On the other hand, when the first switching claw 75 selects the course toward the conveyance path 73 before reversal, the recording sheet P enters the nip of the reversing roller pair 21 via the conveyance path 73 before reversal. The reversing roller pair 21 conveys the recording sheet P sandwiched between the rollers toward the stack portion 50a, and reversely rotates the roller immediately before the trailing end of the recording sheet P enters the nip. Due to this reverse rotation, the recording sheet P is conveyed in the opposite direction, and the rear end side of the recording sheet P enters the reverse conveying path 74.

  The reverse conveyance path 74 has a shape extending while curving from the upper side to the lower side in the vertical direction, and the first reverse conveyance roller pair 22, the second reverse conveyance roller pair 23, and the third reverse conveyance in the path. A roller pair 24 is provided. The recording sheet P is conveyed while sequentially passing through the nips of these roller pairs, so that the recording sheet P is turned upside down. The recording sheet P that has been turned upside down is returned to the above-described sheet supply path 70 and then reaches the secondary transfer nip again. Then, this time, the image transfer surface enters the secondary transfer nip while bringing the non-image carrying surface into close contact with the intermediate transfer belt 8, and the second four-color toner image of the intermediate transfer belt is collectively transferred to the non-image carrying surface. The Thereafter, the sheet is stacked on the stack unit 50a outside the apparatus via the post-transfer conveyance path 71, the fixing device 20, the paper discharge path 72, and the paper discharge roller pair 100. A full color image is formed on both sides of the recording sheet P by such reverse conveyance.

  A bottle support portion 31 is disposed between the transfer unit 15 and the stack portion 50a located above the transfer unit 15. The bottle support portion 31 has toner bottles 32Y, 32M, 32C, 32K serving as toner storage portions for storing Y, M, C, and K toners. The Y, M, C, and K toners in the toner bottles 32Y, 32M, 32C, and 32K are appropriately supplied to the developing units of the image forming units 6Y, 6M, 6C, and 6K, respectively, by a toner conveyance device (not shown). These toner bottles 32Y, 32M, 32C, and 32K are detachable from the printer main body independently of the image forming units 6Y, 6M, 6C, and 6K.

  The reverse conveyance path 74 is formed in the open / close door, and the open / close door has an external cover 61 and a swing support body 62. Specifically, the external cover 61 of the opening / closing door is supported so as to rotate about a first rotation shaft 59 provided in the housing 50 of the printer body. By this rotation, the outer cover 61 opens and closes an opening (not shown) of the housing 50. Further, as shown in FIG. 3, the swinging support 62 of the open / close door is exposed to the outside when the outer cover 61 is opened, and rotates around the second rotation shaft 63 provided on the outer cover 61. It is supported by the outer cover to move. By this rotation, the swing support body 62 swings with respect to the external cover 61 that is opened from the housing 50, and the external cover 61 and the swing support body 62 are separated from each other. 74 is exposed. By exposing the reverse conveyance path 74 in this way, the jam sheet in the reverse conveyance path 74 is easily removed.

  In FIG. 1 described above, the swing support 62 is locked at the first position where it contacts the external cover 61, and the open / close door 60 is closed. The open / close door in such a state forms a post-transfer conveyance path 71 and a paper passage path from the fixing device 20 to the outside of the machine between the swing support body 62 and the main body side of the housing 50. ing. When the opening / closing door 60 is rotated clockwise in the drawing around the first rotation shaft 59 and opened, the main body side of the housing 50 and the swinging support body 62 are separated greatly. By this separation, as shown in FIG. 3, the post-transfer conveyance path 71 and the sheet passing path from the fixing device 20 to the outside of the apparatus are exposed to the outside, and jammed paper in these paths can be easily made. Removed.

  Even if the opening / closing door 60 is opened, most of the transfer unit 15 remains on the main body side of the housing 50, but only the secondary transfer bias roller 19 supported by the swing support 62 moves to the opening / closing door side. To do. One roller of the registration roller pair 28 also moves to the opening / closing door side. In FIG. 1, the printer is shown from the front side in the front-rear direction (front side).

  FIG. 4 is a block diagram showing a part of an electric circuit in the printer. In the figure, a control unit 200 as condition correction means includes a CPU 201, a ROM 202 that stores a control program and various data, and a RAM 203 that temporarily stores various data. The control unit 200 includes an optical writing device 7, T sensors 56 Y, M, C, and K, and an optical writing device 7 via an I / O interface 204 for exchanging signals with each peripheral control unit. The optical writing control circuit 205, the power supply circuit 206, the toner replenishing circuit 207, etc., which are dedicated to controlling the above are connected. An optical sensor unit 150 including a front sensor 151, a center sensor 152, a rear sensor 153, a shared motor 154, and the like is also connected. Each of the front sensor 151, the center sensor 152, and the rear sensor 153 reflects light emitted from a light emitting means (not shown) by a detection target surface of the intermediate transfer belt and detects the reflected light by a light receiving means (not shown). It consists of a photo sensor.

  The optical writing control circuit 205 controls the optical writing device 7 based on a command input from the control unit 200 via the I / O interface 204. Further, the power supply circuit 206 applies a high voltage to the charging device of each image forming unit based on a command input from the control unit 200 via the I / O interface 204, and develops the developing roller of each developing device. Apply a bias.

  The toner replenishing circuit 207 controls a toner conveying device (not shown) for each color based on a command input from the control unit 200 via the I / O interface 204. As a result, toner supply from the toner bottles (32Y, M, C, K) of each color (not shown) to the two-component developer in each developing device is controlled.

  Based on the output values of the T sensors 56Y, M, C, and K for each color, the control unit 200 issues a command to set the toner concentration of the two-component developer in the developing device to a reference level via the I / O interface 204. Output to the toner supply circuit 207.

  This printer is configured to perform the following imaging condition correction processing at a predetermined timing. That is, the optical writing control circuit 205 controls the optical writing device 7 or the like based on a command input from the control unit 200 via the I / O interface 204, or the control unit 200 controls each image forming unit or transfer unit. Are controlled to form Y, M, C, K gradation patterns on the intermediate transfer belt. The Y, M, C, and K gradation patterns are composed of 14 Y, M, C, and K patch toner images each having a predetermined pixel pattern. Each of the 14 Y, M, C, and K patch toner images is formed to have a different toner adhesion amount.

  First, as shown in FIG. 5, the control unit 200 forms a K gradation pattern Kp composed of 14 K patch toner images arranged in the belt moving direction at the center in the width direction of the intermediate transfer belt 8. Then, the central sensor 152 detects the toner adhesion amounts in the 14 K patch toner images. This detection result is sent to the RAM 203 via the I / O interface 204 as an output value Vpi (i = 1 to 14).

  Next, as shown in FIG. 6, the control unit 200 applies the Y gradation pattern Yp composed of 14 Y patch toner images arranged in the belt moving direction to the front side end in the width direction of the intermediate transfer belt 8. Form. At this time, the M gradation pattern Mp composed of 14 M patch toner images arranged in the belt moving direction is formed at the center in the belt width direction so as to be arranged in the belt width direction with respect to the Y gradation pattern Yp. Further, a C gradation pattern Cp composed of 14 C patch toner images arranged in the belt moving direction is formed at the rear side end in the belt width direction so as to be arranged in the belt width direction with respect to the M gradation pattern Mp. . Then, output values Vp <b> 1 to Vp <b> 14 from the front sensor 151 reflecting the toner adhesion amount in the 14 Y patch toner images of the Y gradation pattern Yp are stored in the RAM 203. Further, output values Vp <b> 1 to Vp <b> 14 from the central sensor 152 reflecting the toner adhesion amount in the 14 M patch toner images of the M gradation pattern Mp are stored in the RAM 203. Further, output values Vp <b> 1 to Vp <b> 14 from the rear sensor 153 reflecting toner adhesion amounts in the 14 C patch toner images of the C gradation pattern Cp are stored in the RAM 203.

  Based on the sensor output value stored in the RAM 203 and the data table stored in the ROM 202, the control unit 200 converts each output value into a toner adhesion amount per unit area and obtains the toner adhesion amount data. Stored in the RAM 203. Then, for each of the colors Y, M, C, and K, the development potential and the toner adhesion amount data based on the development potential and the toner adhesion amount data for the 14 patch toner images stored in the RAM 203, respectively. After obtaining an approximate straight line indicating the relationship (development characteristics), a development bias, a photosensitive member uniform charging potential, and the like that obtain a target toner adhesion amount are specified based on the slope of the approximate straight line.

  Once the appropriate development bias and photoreceptor uniform charging potential have been specified for each color in this way, the positional deviation and skew of each color are then detected. Specifically, first, a misregistration detection pattern as shown in FIG. 7 is formed on each of both ends and the center of the intermediate transfer belt 8 in the width direction. Each misalignment detection pattern has eight chevron patch patterns arranged in the belt moving direction (in the figure, only three of the eight sets are shown). One chevron patch pattern includes four orthogonal patches (K orthogonal patch SPk, M orthogonal patch SPm, C orthogonal batch SPc, and Y orthogonal patch SPy) extending in the belt width direction, and is inclined 45 [°] from the belt width direction. And four inclined patches (K inclined patch TPk, M inclined patch TPm, C inclined patch TPc, and Y inclined patch TPy).

  Each patch of the positional deviation detection pattern formed at the front side end in the belt width direction is detected by the front sensor 151. Further, each patch of the positional deviation detection pattern formed at the center in the belt width direction is detected by the center sensor 152. Further, each patch of the positional deviation detection pattern formed at the rear side end in the belt width direction is detected by the rear sensor 153. If the formation timing of each patch is appropriate, the detection time interval of each patch becomes equal, but if it is inappropriate, the detection time interval becomes non-uniform. If there is no skew in the optical system for optical writing, patches of the same color are detected at the same timing between the three misregistration detection patterns. Come different. Based on the detection time interval and detection timing of each patch in the main scanning direction (same as the belt width direction) and sub-scanning direction (same as the belt movement direction), the control unit 200 detects the optical mirror as an image forming condition. The tilt is adjusted and the optical writing timing as an image forming condition is corrected. Such misregistration reduction processing can suppress misalignment of each color and image skew.

  When forming the above-described gradation pattern and misregistration detection pattern, the secondary transfer bias roller 19 is separated from the intermediate transfer belt 8 to avoid dislocation of these patterns to the secondary transfer bias roller 19. It is supposed to be.

  In FIG. 6 shown above, a pressing roller 11 is disposed on the intermediate transfer belt 8. The pressing roller 11 presses the belt portion after passing the winding position with respect to the driving roller 12 from the outside of the belt loop, thereby taking a posture of extending in the horizontal direction with respect to the belt portion on the downstream side of itself. . After passing through the position where the driving roller 12 is hung, the belt portion before entering the pressing position by the pressing roller 11 moves in a posture inclined from the horizontal direction and the vertical direction as shown. The three sensors (151 to 153) of the optical sensor unit face the belt portion that moves in such an inclined posture.

  FIG. 8 is a side view showing the optical sensor unit 150 together with the intermediate transfer belt 8. In the drawing, a front sensor 151, a center sensor 152, and a rear sensor 153 fixed to the outer surface of the side wall of the holder member 156 direct a detection unit (not shown) for entering and emitting light toward the front surface of the intermediate transfer belt 8. . And the attitude | position parallel to the front surface of a belt is taken with respect to the surface of the detection part. A shutter member 160 is slidably attached to the outer surface of the bottom wall of the holder member 156. The shutter member 160 has an elongated plate shape extending in a direction orthogonal to the paper surface. In the state shown in the drawing, the shutter member 160 is located immediately below the three sensors (151 to 153), so that the detection units of these sensors are arranged. Are all closed.

  A cleaning member 161 made of a brush is fixed to the surface of the shutter member 160 facing the sensor, and thereby a gap between the detection unit of each sensor and the shutter member 160 is closed. From this state, as shown in FIG. 9, when the shutter member 160 slides and retracts from directly below the three sensors (151 to 153), the detection units of the three sensors are exposed. As a result, the toner image and the toner adhesion amount can be detected by the three sensors. The shutter member 160 scrapes dirt on the surfaces of the detection units by sliding the cleaning member 161 against the detection units of the three sensors during the sliding movement.

  A backing member 18 is in contact with the three sensors in the entire area in the circumferential direction of the intermediate transfer belt 8 from the back side of the belt loop. As a result, the undulation of the belt in the region facing the three sensors is avoided.

Next, a characteristic configuration of the printer according to the embodiment will be described.
FIG. 10 is a plan view showing the optical sensor unit 150 with the shutter member 160 opened from below. In the figure, a holder member 156 of the optical sensor unit 150 is fixed to a printer body side plate (not shown) in such a posture that its longitudinal direction is along the width direction of an intermediate transfer belt (not shown). The short direction of the holder member 156 is along the moving direction of an intermediate transfer belt (not shown). The shutter member 160 includes elongated holes 160a extending in the belt width direction and in a direction inclined from the belt moving direction, near one end and the other end in the belt width direction. Bolts 158 inserted into the long holes 160 a are screwed into screw holes provided in the holder member 156. Thus, the shutter member 160 is held by the holder member 156 so that it can slide in the extending direction of the long hole 160a. In the figure, for the sake of convenience, only the male screw portion of the bolt 158 is shown, and the hexagonal bolt head is not shown.

  A taper gear 199 shown in FIG. 11 is disposed on the side of the shutter member 160. The tapered gear 199 includes a disk-shaped gear portion 199a and a tapered portion 199b. And the taper part 199b is provided in the side surface of the one end side of the axial direction in the gear part 199a, and becomes a taper shape which loses thickness at once after increasing thickness gradually in a gear rotation direction.

  The shutter member 160 is pulled in the direction of arrow A in FIG. 12 by a tension coil spring (not shown). This arrow A direction is a direction along the width direction of an intermediate transfer belt (not shown) and from the rear side to the front side of the printer main body. In the state in which the shutter member 160 is opened, as shown in the figure, the gear abutting portion 160b provided at the front side end portion of the shutter member 160 is not the tapered portion 199b of the tapered gear 199 but the side surface of the gear portion 199a. Directly hitting. In other words, the taper gear 199 stops at the rotational position where the taper portion 199b does not abut, so that the shutter member 160 stops at the open position in the slide movement direction (extending direction of the long hole 160a).

  It is assumed that the taper gear 199 stops rotating at a position where the top of the tapered portion 199b abuts against the gear abutting portion 160b of the shutter member 160 by a rotational drive of a common motor (not shown). Then, as shown in FIG. 13, the tapered portion 199b pushes the shutter member 160 from the front side to the rear side of the printer main body. Then, the pressed shutter member 160 slides along the elongated hole 160a and stops immediately below the three sensors (151 to 153). Thereby, the detection parts of the three sensors are covered by the shutter member 160.

  FIG. 14 is a partial perspective view partially showing the transfer unit 15 in a state where the secondary transfer bias roller 19 is separated from the intermediate transfer belt 8. In the drawing, abutting rollers 180 are idled on the shaft portion on one end side and the shaft portion on the other end side in the axial direction of the secondary transfer bias roller 19 disposed outside the loop of the intermediate transfer belt 8. It is attached as possible. Also, cam gears 181 are attached to the shaft portion on one end side and the shaft portion on the other end side in the axial direction of the driving roller 12 disposed inside the loop of the intermediate transfer belt 8 so as to be able to idle. The cam gears 181 include a gear portion 181a and an eccentric cam portion 181b that are integrally formed at positions aligned in the axial direction. When the cam gear 181 stops rotating at the illustrated position, the large-diameter portion of the eccentric cam portion 181b of the cam gear 181 hits the abutting roller 180 and pushes the secondary transfer bias roller 19 away from the belt. Then, the secondary transfer bias roller 19 is separated from the intermediate transfer belt 8, and a gap G is formed between the belt and the secondary transfer roller 19.

  On the other hand, when the cam gear 181 stops rotating at the position shown in FIG. 15, the cam gear 181 moves away from the abutment roller 180. As a result, the secondary transfer bias roller 19 contacts the intermediate transfer belt 8 to form a secondary transfer nip.

  FIG. 16 is a partial perspective view showing a part of the transfer unit 15 from the rear side. FIG. 17 is a side view showing a part of the transfer unit from the rear side. In these drawings, on the rear side of the transfer unit 15, a rear side gear group including a driving gear 182, a first relay gear 183, a second relay gear 184, a third relay gear 185, a taper gear 181 and the like is provided. . The transfer unit 15 is held by the printer main body so as to slide in the belt width direction. The belt is slid from the rear side to the front side in the belt width direction to be pulled out from the printer main body. Further, it is mounted on the printer body by being slid from the front side to the rear side. At this time, the common coupling (not shown) fixed to the printer main body is coupled to the coupling portion 182b of the driving gear 182. Further, a driving coupling (not shown) fixed to the rear side end portion of the shaft member 12a of the driving roller 12 and a main body side driving coupling (not shown) fixed to the printer main body are connected. The common coupling is rotated by a rotational drive of a common motor 154 shown in FIG. The main body side drive coupling is rotated by a rotational drive of a drive motor (not shown).

  A first relay gear 183 meshes with a driving gear 182 connected to a common coupling that receives a driving force from the common motor 154. Further, the second relay gear 184 is engaged with the first relay gear 183. The second relay gear 184 is fixed to the rear side end portion of the shaft 198 disposed so as to penetrate the belt loop from the rear side toward the front side. In addition to the second relay gear 184, a third relay gear 185 is fixed to the rear side end. The gear portion 181a of the cam gear 181 described above meshes with the third relay gear 185. When the driving gear 182 rotates, the rotational force is sequentially transmitted to the first relay gear 183, the second relay gear 184, the shaft 198, the third relay gear 185, and the gear portion 181a of the cam gear 181. As a result, the eccentric cam portion 181b of the rear cam gear 181 rotates.

  FIG. 18 is a partial perspective view showing a part of the transfer unit 15 from the front side. FIG. 19 is a plan view partially showing a front side end portion of the transfer unit 15. FIG. 20 is a side view showing the front side gear group of the transfer unit 15 from the rear side. As shown in these drawings, a front side gear group including a cam gear 181, a fourth relay gear 186, a tapered gear 199, and the like is provided on the front side of the transfer unit 15. The fourth relay gear 186 is fixed near the end portion on the front side of the shaft 198 described above. The fourth relay gear 186 meshes with the gear portion 181a of the front cam gear 181 and the gear portion 199a of the tapered gear 199. On the rear side, when the rotational driving force of the driving gear 182 in FIG. 16 is transmitted to the first relay gear 183 and the second relay gear 184 and the shaft 198 rotates, on the front side, the fourth relay gear shown in FIG. 186 rotates. Then, the rotational force is transmitted to the cam gear 181 on the front side, and the eccentric cam portion 181b of the cam gear 181 rotates. At the same time, the taper gear 199 rotates to move a shutter member (not shown).

  As described above, in this printer, as the pressing member that moves the shutter member 160 and the secondary transfer bias roller 19 according to the change in the posture of the printer, the shutter member among the shutter member 160 and the secondary transfer bias roller 19 is used. A taper gear 199 as a shutter pressing member that presses only 160 is provided. Further, a cam gear 181 is provided as a contact / separation pressing member that presses only the secondary transfer bias roller 19 out of the shutter member 160 and the secondary transfer bias roller 19. The taper gear 199 and the cam gear 181 share the common motor 154.

  In such a configuration, since the taper gear 199 and the cam gear 181 are provided separately, the restriction that the shutter member 160 and the secondary transfer bias roller 19 must be disposed at a short distance from each other is eliminated. The degree of freedom can be improved as compared with the prior art. Further, by sharing the common motor 154 between the taper gear 199 and the cam gear 181, the number of parts can be reduced.

  In this printer, the taper portion 199b of the taper gear 199 is brought into direct contact with the shutter member 160. However, the taper portion 199b may be brought into contact with a shutter connecting member connected to the shutter member 160. Also, the eccentric cam portion 181b of the cam gear 181 is brought into contact with the pressing roller 180 connected to the secondary transfer bias roller 19, but the eccentric cam portion 181b is brought into direct contact with the secondary transfer bias roller 19. May be.

  Next, a printer according to an example in which a more characteristic configuration is added to the printer according to the embodiment will be described. Unless otherwise specified below, the configuration of the printer according to the example is the same as that of the embodiment.

  FIG. 21 is a plan view illustrating the optical sensor unit 150 of the printer according to the embodiment from below. In the printer according to the embodiment, the center sensor 152 is slightly shifted from the front sensor 151 and the rear sensor 153 to the upstream side in the belt moving direction. In the figure, the optical sensor unit 150 in a state where the shutter member 160 is completely opened is shown. In this state, the shutter member 160 is retracted from directly below all the optical sensors (151 to 153) to expose the detection units of all the optical sensors.

  FIG. 22 is a plan view showing the optical sensor unit 150 with the shutter member 160 half closed from below. When the rotation stop position of the taper gear 199 is slightly shifted from the state of FIG. 21, the shutter member 160 exposes only the front sensor 151 and the rear sensor 153 as shown in FIG.

  FIG. 23 is a plan view showing the optical sensor unit 150 in a state where it is desired to completely close the shutter member 160 from below. When the rotation stop position of the taper gear 199 is slightly shifted from the state of FIG. 22, the shutter member 160 is in a state of closing all the optical sensors as shown in FIG.

  The printer according to the embodiment performs the image forming condition correction process without interrupting the continuous printing operation every time a predetermined number of prints are performed during the continuous printing operation. However, in this case, unlike the normal image forming condition correction process, various patterns are formed at both ends in the width direction of the intermediate transfer belt and in non-image areas that do not overlap the recording paper. Specifically, first, a Y gradation pattern is formed at the front end of the belt, and an M gradation pattern is formed at the rear end. At this time, a toner image based on the image information is formed in an area excluding both ends of the belt. Next, a K gradation pattern is formed at the front end of the belt, and a C gradation pattern is formed at the rear end. Also at this time, a toner image based on the image information is formed in an area excluding both ends of the belt. Next, a positional deviation detection pattern is formed on each of the front side end portion and the rear side end portion of the belt. Also at this time, a toner image based on the image information is formed in an area excluding both ends of the belt.

  When such an image forming condition correction process for continuous printing operation is performed, as shown in FIG. 22, the shutter member 160 is opened by half and only the front sensor 151 and the rear sensor 153 are exposed. As a result, various patterns formed on both ends of the belt can be detected by the front sensor 151 and the rear sensor 153.

  In addition, when the execution timing of the image forming condition correction process comes when the control unit 200 is not in the continuous printing operation, the control unit 200 performs the image forming condition correction process similar to that described in the embodiment. At this time, as shown in FIG. 21, the shutter member 160 is completely opened to expose all the optical sensors (151 to 153). Thereby, various patterns can be detected by the three optical sensors.

The embodiments and examples described above are merely examples, and the present invention has specific effects for each of the following modes.
[Aspect A]
In the aspect A, as in the printer according to the embodiment, the surface endless moving body such as the intermediate transfer belt 8 is wound around a stretching member such as a plurality of stretching rollers disposed inside the loop itself. An endless belt member that can be moved endlessly in the state of being used is used. In addition, as one of the plurality of stretching members, a driving roller 12 that moves the belt member endlessly as it rotates in a posture in which its own axial direction follows the width direction of the belt member is used. Further, a shaft 198 disposed so as to extend along the belt width direction inside the loop, and a rear that idles on a peripheral surface of a first shaft portion that is a shaft portion on the rear side in the axial direction of the drive roller 12. The first idle gear such as the gear portion 181a of the side cam gear 181 and the gear portion 181a of the front cam gear 181 that idles on the peripheral surface of the second shaft portion that is the axial portion of the drive roller 12 in the axial direction. Mesh with the second idler gear, the first idler gear fixed to the rear end in the axial direction of the shaft 198 to mesh with the first idler gear, and the second idler gear. As described above, a second shaft gear such as a fourth relay gear 186 is provided which is fixed to an end portion on the front side in the axial direction of the shaft 198. Further, a first eccentric cam such as an eccentric cam portion 181b that presses its own cam surface against a rear side portion in the belt width direction of the contact / separation member such as the secondary transfer bias roller 19 or the contact / separation connection member is attached to the first idling gear. Along with the gear portion, the idle rotation is performed on the peripheral surface of the first shaft portion. Further, the second eccentric cam such as the front cam gear 181 that makes its own cam surface abut on the front side portion of the contact / separation member or the contact / separation connecting member in the belt width direction together with the second idling gear is arranged around the second shaft portion. I try to idle on the surface. In such a configuration, similarly to the printer according to the embodiment, the space on the loop side of the belt member (for example, the intermediate transfer belt 8) is used, and the driving force on the rear side is applied to the front by the shaft 198 disposed in the space. Therefore, space can be saved as compared with the case where the drive is transmitted from the rear side to the front side outside the loop.

[Aspect B]
In the aspect B, as in the printer according to the embodiment, as a shutter pressing member such as the eccentric cam portion 181b, the shutter member includes a taper extending along the rotation direction thereof at one end portion in the rotation axis direction of the shutter member. Alternatively, a member that changes the pressing amount by changing its own rotation stop position while pressing a taper (for example, the taper portion 199b) against one end or the other end of the shutter connecting member in the belt width direction is used. In such a configuration, similarly to the printer according to the embodiment, the amount of pressing against the shutter member or the shutter connecting member can be slightly changed by the rotation stop position of the shutter pressing member (for example, the taper gear 199). And the number of sensors which have closed the detection part can be changed freely by the delicate change of the amount of pressing.

[Aspect C]
In the aspect C, similarly to the printer according to the embodiment, the optical units such as the optical sensor unit 150 are arranged at different positions in the belt width direction and at different positions in the belt member moving direction. In addition, a device having a plurality of optical sensors is used. Further, the shutter member 160 that is pushed in the belt width direction by the taper of the shutter pressing member (for example, the taper portion 199b) guides the shutter member 160 along the inclination direction that is the direction inclined from the belt width direction while being along the surface of the belt member. Guide means such as holes 160a are provided. Further, by changing the position of the shutter member 160 in the tilt direction by changing the pressing amount at the taper, the number of optical sensors in the state where the detection unit is closed by the shutter member 160 is changed. In such a configuration, the number of optical sensors in a state where the detection unit is closed can be easily changed by driving one common motor.

[Aspect D]
In aspect D, like the printer according to the embodiment, the shutter member 160 is translated along the surface of the detection unit of the optical sensor. In addition, a cleaning member 161 that performs a cleaning process by rubbing on the surface of the detection unit is provided as the shutter member 160 is fixed and moved together with the shutter member 160. In such a configuration, by moving the shutter member 160 in parallel along the surface of the detection surface, the cleaning member 161 is moved in parallel to the detection surface, and an even rubbing force is exhibited. Thereby, compared with what changes rubbing force by non-parallel movement, generation | occurrence | production of the damage of a detection surface can be suppressed.

1Y, M, C, K: photoconductor (image carrier)
6Y, M, C, K: Image forming unit (part of toner image forming means)
7: Optical writing device (part of toner image forming means)
8: Intermediate transfer belt (surface endless moving body, belt member)
12: Driving roller 15: Transfer unit (transfer means)
19: Secondary transfer bias roller (contact / separation member)
150: Optical sensor unit (optical unit)
151: Front sensor (optical sensor)
152: Center sensor (optical sensor)
153: Rear sensor (optical sensor)
154: Common motor (drive source)
155: Third relay gear (first shaft gear)
156: Fourth relay gear (second shaft gear)
160: Shutter member 160a: Long hole (guide means)
161: Cleaning member 181: Cam gear (contact / separation pressing member)
181a: Gear portion (first idle gear, second idle gear)
181b: Eccentric cam portion 198: Shaft 199: Taper gear (shutter pressing member)
199a: Gear portion 199b: Tapered portion

Japanese Patent Laid-Open No. 2002-006568 JP 2001-0334030 A JP 2009-145778 A

Claims (5)

Toner image forming means for forming a toner image on the surface of the image carrier;
Endlessly moves the surface of the endless belt member , which is endlessly moved while being wound around a plurality of stretching members disposed inside the own loop, along a path for entering the position facing the image carrier. A transfer means for transferring the toner image on the image carrier to the surface of the belt member or the recording material held on the surface at the facing position;
An optical sensor that detects an optical characteristic of a region where a predetermined test toner image is formed out of the entire region in the direction orthogonal to the moving direction of the belt member, a holding body that holds the optical sensor, and a detection unit of the optical sensor. An optical unit comprising a shutter member that opens and closes;
Condition correcting means for correcting the image forming condition of the toner image forming means based on the detection result by the optical sensor;
A contacting / separating member contacting and separating from the surface of the belt member ;
The shutter member or its linked shutter connecting member, and one of the contacting and spacing member or its linked separable connecting member, is disposed so that per press only the shutter member or the shutter connecting member , by varying the amount of pushing by a change in its posture, the shutter pressing member for operating said shutter member,
Among the shutter member or the shutter connecting member, and the contact / separation member or the contact / separation connecting member, the shutter member or the shutter connecting member is disposed so as to press only the contact / separation member or the contact / separation connecting member, and is pushed by a change in its own posture. A contact / separation pressing member that operates the contact / separation member by changing a contact amount;
Exert driving force for driving the shutter pressing member and the contact and separation pressing member, an image forming apparatus and a drive source shared in the shutter pressing member and the contact and separation pressing member,
A shaft disposed inside the loop and extending along the width direction of the belt member;
A shaft portion on one end side in the axial direction of a driving roller that moves the belt member endlessly as it is driven to rotate in a posture in which its axial direction is along the width direction among the plurality of stretching members. A first idle gear that idles on the peripheral surface of the one shaft portion;
A second idling gear that idles on a peripheral surface of a second shaft portion that is a shaft portion on the other end side in the axial direction of the drive roller;
A first shaft gear fixed to an end on one end side in the axial direction of the shaft so as to mesh with the first idling gear;
A second shaft gear fixed to the other end of the shaft in the axial direction so as to mesh with the second idling gear;
A first eccentric cam as the contact / separation pressing member that presses its own cam surface against one end side position in the width direction of the contact / separation member or the contact / separation connecting member together with the first idling gear is the first shaft portion. To idle on the circumference of the
In addition, the second eccentric cam as the contact / separation pressing member for bringing its own cam surface into contact with the other end side position in the width direction of the contact / separation member or the contact / separation connecting member together with the second idling gear. An image forming apparatus characterized by being idled on a peripheral surface of a second shaft portion . The image forming apparatus according to claim 1 .
As the shutter pressing member, a taper extending along the rotation direction of the shutter is provided at one end of the rotation axis direction of the shutter, or the shutter member or the shutter connecting member with respect to one end or the other end in the width direction. An image forming apparatus using an apparatus that changes a pressing amount by changing its own rotation stop position while pressing a taper. The image forming apparatus according to claim 2 .
As the optical unit, a unit comprising a plurality of the optical sensors disposed at positions different from each other in the width direction and at positions different from each other in the moving direction of the belt member,
Providing a guide means for guiding the shutter member pushed in the width direction by the taper along an inclined direction which is a direction inclined from the width direction while being along the surface of the belt member;
The number of optical sensors in a state in which the detection unit is closed by the shutter member is changed by changing the position of the shutter member in the tilt direction according to the change in the pressing amount. Image forming apparatus. The image forming apparatus according to any one of claims 1 to 3 ,
While causing the shutter member to translate along the surface of the detection unit,
An image forming apparatus, comprising: a cleaning member that performs a cleaning process by rubbing on a surface of the detection unit as the shutter member is fixed to the shutter member and moves together with the shutter member. While endlessly moving the surface of an endless belt member that is endlessly moved in a state of being wound around a plurality of stretching members disposed inside the loop of the own loop, the surface of the endless belt member enters a position facing the image carrier. Transfer means for transferring the toner image on the image carrier to the surface of the belt member or a recording material held on the surface at the facing position;
An optical sensor that detects an optical characteristic of a region where a predetermined test toner image is formed out of the entire region in the direction orthogonal to the moving direction of the belt member, a holding body that holds the optical sensor, and a detection unit of the optical sensor. An optical unit comprising a shutter member that opens and closes;
A contacting / separating member contacting and separating from the surface of the belt member ;
The shutter member or its linked shutter connecting member, and one of the contacting and spacing member or its linked separable connecting member, is disposed so that per press only the shutter member or the shutter connecting member , by varying the amount of pushing by a change in its posture, the shutter pressing member for operating said shutter member,
Among the shutter member or the shutter connecting member, and the contact / separation member or the contact / separation connecting member, the shutter member or the shutter connecting member is disposed so as to press only the contact / separation member or the contact / separation connecting member, and is pushed by a change in its own posture. A contact / separation pressing member that operates the contact / separation member by changing a contact amount;
Exert driving force for driving the shutter pressing member and the contact and separation pressing member, in a transfer unit and a driving source shared with the shutter pressing member and the contact and separation pressing member,
A shaft disposed inside the loop and extending along the width direction of the belt member;
A shaft portion on one end side in the axial direction of a driving roller that moves the belt member endlessly as it is driven to rotate in a posture in which its axial direction is along the width direction among the plurality of stretching members. A first idle gear that idles on the peripheral surface of the one shaft portion;
A second idling gear that idles on a peripheral surface of a second shaft portion that is a shaft portion on the other end side in the axial direction of the drive roller;
A first shaft gear fixed to an end on one end side in the axial direction of the shaft so as to mesh with the first idling gear;
A second shaft gear fixed to the other end of the shaft in the axial direction so as to mesh with the second idling gear;
A first eccentric cam as the contact / separation pressing member that presses its own cam surface against one end side position in the width direction of the contact / separation member or the contact / separation connecting member together with the first idling gear is the first shaft portion. To idle on the circumference of the
In addition, the second eccentric cam as the contact / separation pressing member for bringing its own cam surface into contact with the other end side position in the width direction of the contact / separation member or the contact / separation connecting member together with the second idling gear. A transfer unit characterized by being idled on the peripheral surface of the second shaft portion .

Images